It's a waste of your money. Don't buy it. Don't give them an excuse to make more crappy games like this one.
Infernal, initially, dares to be different. Here, you're the bad-guy. You go around and kill good-guys. "COOL!" you might think. But no. This game is just like EVERY other mediocre game out there. You go around killing the same brain-dead guys, with the same lame weapons you've seen in a million games before. Uh, no. Make that a billion games. You're "evil". Exactly. "Evil". It's just a word. They've exchanged the old "Good"-word with a new "Evil"-word, but in the process of changing the words, they forgot to change the GAME itself from the masses. It's just like every other. The story is so dull that you'll find it in any James Bond Movie (well, except for the word "evil") - only the Bond-movies have a deeper story (can you believe that?).
Infernal has got flashy (but dull) graphics, and the sound isn't the worst (just mediocre enough). When the technical stuff is the only thing "good" this game has to offer, then it's obvious that it's not worth your money.
I would have given this a 5.0, since it's so mediocre - but since the developer has been so bold to try to fool us into thinking that this game sticks out from the crowd, I give it 4.6. It's a waste of your money. Don't buy it. Don't give them an excuse to make more crappy games like this one.